We are requesting funding for a Thermo Finnigan LCQdecaXP+ ion trap mass spectrometer. Characterization of multi-protein complexes has become one of the most powerful methods for elucidating protein/gene function and for understanding how normal cellular functions, as well as, pathological conditions, such as cancer or diabetes, are controlled by these multi-protein complexes. This type of analysis provides an important foundation for understanding gene function and has become a critical component of research at Cold Spring Harbor Laboratory. In recent years, mass spectrometry has superceded other techniques for protein identification and characterization. This is largely due to the enhanced sensitivity, through put and flexibility provided by mass spectrometry. The Protein Chemistry Shared Resource in the Cold Spring Harbor Laboratory Cancer Center has become increasingly reliant on mass spectrometry and is requesting funding for a Thermo Finnigan LCQdeca XP+ mass spectrometer. The LCQdeca XP+ is a state of the art ion trap mass spectrometer, which is renowned for its sensitivity and analytical capabilities. The new instrumentation will enhance the sensitivity, reliability, and through put of this critical application and will have a major impact on the shared users of this grant and the larger Cold Spring Harbor community. This instrument will be incorporated into an existing mass spectrometry based protein chemistry shared resource, and will therefore be integrated into an existing organization that will oversee the management, operation, and maintenance of the new instrument. [unreadable] [unreadable]